Piano key easing machine



N0V 36, 1954 M. A. .JAcoBsoN ETAL 2,694,359

PIANO KEY EASING MACHINE 2 SheetS-Sheet l Filed Jan. 25, 1951 NOV- 16, 1954 M. A. JAcoBsoN ET AL 2,694,359

' PIANO KEY EAsING MACHINE Filed Jan. 25. 1951 2 Sheets-Sheet 2 United States Patent() PIANO KEY EAsING MACHINE Mason A. Jacobson and Harold J. McGetrick, De Kalb, lll., assignors to The Rudolph Wurlitzer Company, Chicago, lll., a corporation Application January 25, 1951, Serial No. 207,778

7 claims. (ci. 10o-49) This invention relates to a piano key easing machine for providing the felt lined slots of a key openingwith proper and accurate pin clearance.

The standard piano keyboard comprises a plurality of pine or bass wood keys, each having a slotted opening at the balance point and another slotted opening at the front which projects into the bottom of the key. Both slotted openings have their side walls lined with felt. Each key is inserted over a pin at the balance point of the keyboard so that when the key is depressed the front pin of the keylloard extends into the slotted opening at the front of the In the standard keyboard there are 88 keys and it is necessary in the process of regulating the piano for proper playing that correct and accurate clearance be obtained between the walls of the slotted openings for the balance pin and the front pin. To achieve this end, the accepted procedure is to ease each key at the balance point and front opening by means of special hand manipulated pliers, which the regulating mechanic inserts in the slotted openings of the key to compress the felt and the wooden wall by hand until he is satisfied through feel or touch that the correct clearance is obtained. Such hand manipulating method is not only tiring and requires an expert mechanic of long experience and training but is nonuniform because the mechanic finds it difficult to maintain the same amount of compression on the felt and wooden walls at all times, particularly during the later fatiguing hours of the work day.

It is therefore the object of this invention to provide a simple and effective machine for easing piano keys which may be manipulated by inexperienced help, and wherein the easing operation is at all times uniform and accurate by applying the same amount of compression to each key wall. This is accomplished by providing a pair of spreaders which not only engage and compress the felt and wooden walls of the key opening to a predetermined and exact extent, but maintain them under compression during a predetermined time period for effecting the accurate setting thereof.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

Fig. l is a perspective view of the machine with parts' remo/ed, parts broken away and parts schematically illustrate Fig. 2 is a central vertical section through the clamping jaws and spreaders with a piano key in processing position.

Fig. 3 is a perspective view of the time control mechanisrn.

Fig. 4 is an enlarged view partially in section, and parts removed, showing the spreaders in easing engagement with a piano key.

Fig. 5 is the same as Fig. 4 showing the spreaders in released position.

In the drawings there is illustrated a piano key easing machine having a supporting base and a housing 11 mounted thereon. Supported on top of the housing there is a bed plate 12 carrying on opposite sides thereof in opposed spaced relation a set of guide blocks 13. Slidable between each pair of guide blocks there is a clamping slide 14 bifurcated at one end thereof. Each of said clamping slides carries a clamping jaw 15 pivotally connected thereto adapted to engage and clamp a piano key 16 therebetween as shown in Figs. 2 and 4.

Mounted below the bed plate 12 there is provided a cam head 17 having outwardly extending opposed cani lCC surfaces 18 terminating in an inwardly formed recess portion 19 extending thereabove. The cam head is carried by a piston rod 20 extending into an air cylinder 21 in which a piston indicated at 22 connected with the piston rod is cause to operate through air pressure. Bolted to the underside of the bed plate, as at 12a to extend downwardly therefrom, there is a mounting bracket 23 having laterally -extending bifurcated arms 24 and a lower guide portion for slidably receiving the cam head 17.

Fulcrumed intermediate the arms 24 on each side of the bracket there is a clamping lever 25. The lower end of each lever is provided with a pair of cam rollers 26 normally riding in the recessed portion 19 of the cam head when in its lowered position, and upon the outwardly extending cam surfaces 18 when in its raised position.

The upper ends of the clamping levers are formed with the actuating fingers 27 each extending through a slot 28 in the bed plate into the bifurcated ends of the clamping slides 14 respectively. The actuating fingers of each of said levers is urged outwardly, and the rollers inwardly to bear upon the cam surface by the compression springs 29. Said springs are interposed between the upper portion of each lever and the adjacent portion of the bracket 23.

When air is forced into the cylinder 21 the cam head is raised to spread the cam rollers 26 and force the fingers 27 toward each other for causng the clamping jaws to engage and clamp the piano key 16 therebetween. When air is exhausted from the cylinder the cam head drops by gravity due to its weight so that the cam rollers ride into the recessed portions 19 of the head permitting the springs 29 to spread the actuating fingers and clamping jaws 15 for releasing the piano key.

In axial alignment with the piston rod 20 and slidably mounted in the bracket 23 there is a spreader holder 30. The lower end of said holder abuts an adjustable thrust screw 31 carried by the cam head. Fulcrumed at the upper end of the spreader holder are the spreaders 32, each having an upwardly extending lip portion 33 and a laterally extending arm portion 34, the fulcrum point of the spreader being intermediate the lip and arm portions.

Each spreader is also formed with the downwardly extending tail portion 35, and between said tail portions and supported therein there is a compression spring 36. The lip portions of the spreader extend upwardly through an aperture in the bed plate between the clamping jaws and in position to enter the slotted opening 16b of the key 16. The underside of the bed plate is provided with a pair of stops 37 arranged for engagement by the extended ends of the respective arm portion 34 of the spreader.

The above described arrangement of the spreader is such that when the cam head is elevated it causes the key to be gripped by the jaws 15, the adjustable thrust screw 31 engages the spreader holder 30 and moves the holder and the spreaders upwardly to cause the lip portions 33 to freely enter the slotted opening of the key. After the lip portions have thus entered the key. continued movement of the cam head and spreader holder causes the laterally extending arm portions 34 to engage their respective stops 37.

The final upward thrust. through the medium of the arms and stops, causes the lip portions to spread laterally to a predetermined distance into compressing engagement with the felt 16a glued to the wooden wall of the slotted opening. Thus the slotted opening and felt is eased to a predetermined extent. This easing .engagement thereof then continues for a predetermined time as further described.

The machine is connected with a source of compressed air not shown, connected through a pressure switch 40 with a high pressure air line 41. Said high pressure air line is controlled by an air solenoid valve mounted within the valve housing 42 which in turn is connected through the air line 43 with the underside of the air cylinder 21. The air solenoid valve is also connected with an exhaust air line 44. Said air solenoid valve is controlled through an electric circuit from a relay and timer schematically indicated in the housing 45. Said relay and timer is actuated by a micro-switch 46 (Fig. 3) in the usual manner.

The above described air control and timing is merely illustrated schematically in that any of the well known the key.

and understood air solenoid valves, relay and timers,

"pressure and micro-switches vmay be `employed inY the 'fulcrumed to a suitable boss on the housing 11. The

inner end of the lever is connected with a control yrod 48 having its upper free end extending through and guided within an opening 49 in the bed plate 12 fimmediately below the piano key to be engaged `thereby and pressed downwardly when the key is placed in operative position. The relay and timer is set to reverse the `air solenoid valve indicated lat 42 VAat a predetermined time after the operating cycle is initiated through actuation of the micro-switch by lpressing the key in `operative position. Thetiming is predetermined to eiect maintenance of the spreading and compressing action 'in the slotted opening to permit the compressed felt -and 'wood to set.

In operation, when a piano key is placed in position on 'the bed plate, as shown in Figs. v2 and 3, the co'ntrol rod 48 is pressed downwardly by the key causing `the micro-switch to start the timer and open the air solenoid valve to admit air into the cylinder 21. Thus the cycle and timing of the operation is initiated. The cam head 17 is forced upwardly causing the jaws 15 to yclamp the key. Thereupon the arm portions 34 of the spreader are forced upwardly by the holder through screw v31, into engagement with the stops 37 causing the lip portions 33 thereof to move outwardly into vspreading 'and compressing engagement with the felt lined walls of the slotted opening 16h in the key 16.

The extent of the spreading and compressing action has been predetermined by the setting of the adjustable thrust screw 31. After a predetermined time 'interval in which the spreading and compressing action has been maintained, the relay and timer `indicated at 45 actuates the air solenoid valve 42 to shut oit the air source through the line 41 and openthe line-43 to the exhaust line 44 for exhausting air from the cylinder 41. The cam head then drops releasing and withdrawing the spreaders and opening the clamping jaws 'for removal of It will therefore be observed that during Vthe cycle of operation the felted slotted -openin'g in the key will have received a predetermined spreading and cornpressing torce over a predetermined time interval to effect the setting thereof.

The invention claimed is:

l. A piano key easing machine including means for securing a piano 'key-having a felt lined slotted opening therein operative position on said machine, a spreader including lips mounted on said machine adapted to extend into the felt lined slottedl opening of the positioned key for deforming the. same, and -power operated mechanism operable to force said-spreader against opposite walls` of `the slotted opening to a .predetermined extent and over a-predetermined timeinterval forpermanently establishing the deformation of the felt and key Yand means operable by positioning of the key in operative position on said machine -for receiving saidAspreader-t'o initiate said power operated mechanism.

2. A vpiano key easing machine including means for securing a piano key having a felt lined slotted opening therein in operative position on said machine, a spreader including lips mounted on said machine adapted to 'extendinto the felt lined slotted opening of the positioned key -for deforming thesame, .power operated mechanism operably connected with said spreader to force it against opposite walls of the slotted opening to a predetermined extent, and a -time control means connected with 'said mechanism 'for maintaining said spreader in its spreading position for .predetermined time interval to -permanently establish the deformationof the felt and key and to release said spreader for disengagement from said vwalls at the conclusion of said time interval.

3. A piano key easing machine including a .pair lot' clamping jaws positioned to clamp a keyplaced `therebetween, a spreader including lips mountedto extend between said jaws into. a felt lined slotted opening in the positioned key for deforming the same, and lpower operated mechanism initiated by the positioning 'of 'the key between said jaws .to 'effect a clamping action ofs'ai'd jaws and force said spreader againstropposte Wallsof the slotted opening to a predetermined extent and over 'a'predeterrnined time linterval to permanently establish deformation of the felt and key.

4. A piano key easing machine including a pair of clamping jaws positioned to clamp a key placed therebetween, said key being provided with a slotted opening having felt lined walls,` -a 'pair of spreaders including lips mountedfto extend between said Vjaws yinto said opening, powei 'operated mechanism operably connected with said jaws .and spreaders toleffect a clamping action of said jaws and `force said spreaders against opposite walls of the slotted opening' to a predetermined extent for deforming said walls, a time control element positioned to be r'engaged upon the key being placed between said jaws for initiating operation of said mechanism, and a time control for effect-ing and maintaining said clamping and spreading action over a predetermined time interval for permanently establishing deformation of said 'Wall`s, 'said time control being operable to release rs'aid 'jaws/and spreader to 'permit removal of said key at thecompletion of said time interval.

'5. A 'piano key yeasing 'machine including a bed lplate for 'receivingja 'piano key having a felt lined slotted opening therein, a pair yotfclamping jaws positioned to clamp 1said key Ltherebetween,a -.pair of spreaders in- "cluding flips mounted lto extend through said bed plate -into the opening `of fs'aid key, a cam head movable into "camming engagement with 'said jaws, a spreader holder 'movableby said cam head to force `said spreaders laterally against 4opposite walls of the slotted opening to apreidetermined Yextent, and power --operated mechanism v ladt-ifptedto move 'said 'earn 'head intocamming position -to -eiect fthe 'clamping action of fsaid jaws and maintain said spreaders in p'osit'ionto compress the 'opposite walls 'f the slotted 'opening to 'a predetermined extent.

f6. A 'piano key easing machine including'a Abe'd plate forreceiving a piano key having a felt lined slotted -opening therein, a j'pair of Aclamping jaws positioned to fclam'p said key therebetween,A ja .pair of spreaders mounted to extend through 'sad `bed plate into `the 'opening 'df 'said key, a ,cam head movable into camming engagement with said jawsga 4spreader holder movable 'bly said carnl head totfo'rce said'spreader's laterally against opposite walls of the fslo't'tedopening to a 4predetermined extent, power'oper'ated mechanism adapted tomove 4said v -cam 'head into Acarni-ning position to eiect the clamping action of said jaws and maintainsaid spreaders in positio'n to'c'otnpress the 'opposite walls of Athe `slotted openi'ng to a predeterminedfextent, and` a time controlfor said mechanism ffor causing vit to release said spreaders and jaws after a Apredetermined time interval.

7. A pianokey easing 'machine including abcd plate for receiving a piano key 'having a felt lined slotted openingtherein, a pair 'of clamping jaws positioned to clampsaid'keytherebetween, a pair o'f spreaders mounted toextendthrough `saidbed plate 'in'to the lopening of said key, 'a cam 'head Amovable into camming engagement with said jaws, `a spreader holder movable by 'said vcam head 'tojforce said spreaders :laterally against 'opposite w'allsofthe slotted opening't'o a'predetermine'd extent, an adjustable abutment betweenv said cam head-and spreader holder 'for 'adjustabl'y 'determining 'thejextent of the AVspreading action, and power operated mechanism adapted to move said cam head into camming .position tri-effect the clamping actionrof'said jaws 'and maintain saidspreaders'in'position to compress the opposite walls ofthe Yslotted opening' to 'a 'predetermined extent.

leferencesfited:inthe K'tile of this patent Un 'ED STATES PATENTS Numberv IName v DateA l 788,968 Walker May 2, 1 905 '788,969 AfWzllker May`2, 1905 1,804,162 lKershaw v May` 5, 1931 2,119,617 Winkley 1 IJune 7, 1 938 '2,17530'45 IkSirois Sept. l2, 1939 2,251,324l Carlson Y.- Aug. 5, 19'41 123021327 Kane 'Dec. 15,11942 f23376-67 'Kuel'il'rnan Dec. 28, 1943 

